FIG. 1 is a schematic showing a typical IMD 100, which is suitable for therapy delivery, implanted at a subcutaneous pectoral site in a patient 102. FIG. 1 illustrates IMD 100 including a hermetically sealed and biocompatible canister 104, for example, formed from a Titanium alloy, which houses a power source and electronic circuitry, and one or more electrical leads 106, which are coupled to the circuitry and extend distally from canister 104, through the venous system 110 and into the heart 108 of patient 102, for example, the right ventricle (RV). Those skilled in the art understand that the one or more leads 106 preferably include sensing and therapy delivery electrodes, which are coupled to the IMD circuitry via one or more lead connectors that terminate elongate insulated conductors of the electrodes, at a proximal end of lead(s) 106; the one or more lead connectors are plugged into a connector module 105, which is mounted on canister 104, to make electrical contact with the contained IMD circuitry via hermetically sealed feedthroughs.
FIG. 2 is a simplified circuit diagram of a portion of power source circuitry that may be employed by IMD 100. In particular FIG. 2 illustrates a plurality of batteries 22 in combination with switching circuitry 24, which may form one of a number of battery modules selectively connected in either a parallel or a series configuration and employed by the power source to store and discharge energy for pacing and/or defibrillation therapy, for example, through lead(s) 106 (FIG. 1). FIG. 2 further illustrates switching circuitry 24 including a solid state switch 241 and a switch driver unit 243 that receives trigger pulses, for example, from sensing circuitry (not shown), and, in response, provides a voltage output to cause switch 241 to conduct for discharge of the power source.
Each of batteries 22 may be a planar solid state type, for example, like a battery 32 shown in FIGS. 3A-B. United States Patent Application Publication No. 2006/0129192 and commonly assigned U.S. Pat. No. 6,782,290 describe, to different degrees, the general construction of exemplary planar solid state batteries and the arrangement of such batteries in modules or stacks, as a means to create a more compact/higher density power source in implantable medical devices. However, there is still a need for improved stack configurations and methods facilitating more efficient fabrication of relatively high density power sources from a plurality of solid state planar batteries.